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Characterisation of temporal vision in congenital stationary night blindness

Ba-Abbad, Rola; (2018) Characterisation of temporal vision in congenital stationary night blindness. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Congenital stationary night blindness (CSNB) is a rare hereditary retinal condition, which manifests as visual dysfunction with variable severity. In this thesis temporal acuity and contrast sensitivity are assessed in subjects with molecularly confirmed CSNB to associate their functional losses with the molecular pathology. L-cone temporal acuity (critical fusion frequency or CFF) as a function of retinal irradiance, and L-cone temporal contrast sensitivity as a function of frequency (TCSF) were measured using standard methods in probands with CSNB and carriers of the same mutations, and in ten controls. A rapid-On or rapid-Off sawtooth modulated, 650-nm stimulus, with a diameter of 4⁰, was produced with a Maxwellian-view system. Differences in CFF and TCSF between probands, carriers, and controls were modelled. Six unrelated probands with CSNB1 and mutations in NYX (3), GRM6 (2), TRPM1 (1), and three males with CSNB2 (CACNA1F mutations) participated. For both CFFs and TCSFs in patients with CSNB1 and CSNB2, no consistent differences were found between rapid-On and rapid-Off sawtooth flicker. CSNB subjects showed a broad range of temporal acuity and contrast sensitivity losses. The differences between the TCSF function in controls and probands can be modelled as a simple low-pass filter. Temporal acuity and contrast sensitivity data suggest that the severity of loss is independent of the genotype, but the GRM6-related phenotype was the most severe. In the absence of other pathologies, CSNB provides an example of a non-progressive disorder of the first retinal synapse, which is less likely to be confounded by cell death and inner retinal remodelling. Surprisingly, given the Off-pathway preservation in CSNB1, there is no difference in sensitivity for rapid-On and rapid-Off stimuli.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Characterisation of temporal vision in congenital stationary night blindness
Event: UCL (Univeristy College London)
Language: English
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology
URI: http://discovery.ucl.ac.uk/id/eprint/10055259
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